1. On October 20, 1864, the Idaho Territory was officially established by an act of Congress. This created a separate governing body for the region, which had previously been part of the larger Oregon Territory.

2. In 1890, on October 20th, the first train arrived in Boise, Idaho. This marked a significant milestone in the state's history, as it meant easier transportation of people and goods to and from the capital city.

3. On October 20, 1905, the cornerstone for the Idaho State Capitol building was laid. Built in the Neoclassical style, the building has become an iconic symbol of the state.

4. In 1937, on October 20th, the first-ever potato harvest festival was held in Shelley, Idaho. Today, the Idaho Potato Commission promotes the state's potato industry with events like the Famous Idaho Potato Bowl and the Big Idaho Potato Truck.

5. On October 20, 1983, the Sun Valley Resort in Idaho hosted the first-ever international symposium on environmental philosophy. This gathering brought together scholars from around the world to discuss environmentalism and sustainability, topics that remain relevant today.